All the vacuum cleaners on the current market are arranged with a filter device for filtering suctioned dust-laden air and leaving dust particles in a dust collecting device. The filter device should be cleaned or replaced after the vacuum cleaner has been used for a period of time, otherwise, fine dust may clog filter holes of the filter device, which will increase resistance of the vacuum motor, even burn the motor out, thereby not only bringing trouble to users, but also adversely affecting performance and life-span of the vacuum cleaner.
In recent years, a cyclone dedusting device is used to replace the filter device by manufacturers according to the principle of cyclone separation, which has a better dedusting effect and is widely used in vacuum cleaners. A conical barrel with a larger upper end and a smaller lower end is mounted in the tank of the cyclone dedusting device, and a wind outlet tube is disposed in a longitudinal direction at the upper end of the conical barrel, the lower end of the conical barrel is opened so as to allow dust to fall into the bottom of the tank, a wind inlet tube enters a sidewall of an upper portion of the conical barrel along a tangent direction, so that the dust-laden air flow forms cyclone in the conical barrel, and the dust particles fall into a bottom of a dust collecting barrel along the sidewall of the conical barrel by centrifugal force. The dedusted air flows upwards and is expelled out through the wind outlet tube.
However, the cyclone dedusting device described above has a relatively larger bulk, and an especially larger bulk is required while it is used in a large vacuum cleaner requiring a relative larger air flow, which not only increases manufacturing cost thereof, but also brings much inconvenience to users.
Besides, the cyclone barrel of the dedusting device described above is in a reversed conical shape with a larger upper end and a smaller lower end and separates dust by accelerated rotation of air flow. As a result, air flow pressure loss is relatively high, which adversely affects dust suction effect of the vacuum cleaner.
Furthermore, the accelerated air flow may easily raise again the fine dust which have fallen to the bottom of the dust tank, and the raised fine dust will be expelled out from the wind outlet tube with the air flow, thereby resulting in secondary pollution. So the device is more suitable for separating coarse particles and is less effective in separating fine particles.